This invention relates to a process and apparatus for texturing thermoplastic yarn and to yarn made thereby.
Many procedures are available for the treatment of thermoplastic mono- or multi-filament yarns to "texture" them, that is, to crimp the yarn, thereby rendering them more voluminous or bulky. While entangling of multi-filament yarns also contributes to bulk, entangling normally is a separate operation from crimping and is not considered to be "texturing". Texturing procedures include a number of processes in which the yarn is subjected to treatment by a stream of fluid such as air or steam. It is also well recognized that permanent texture and bulk requires that the treatment be carried on at temperatures above the plasticizing temperature of the yarn. The texturing is non-permanent, if, when the yarn is pulled slightly and released, the deformations are substantially removed so that the filaments appear to be generally straight and parallel to one another. Texturing is permanent when the deformed yarn, after such pulling and release, returns substantially to the crimped and bulked condition it was in before being pulled.
Descriptions of prior art processes for texturing of thermoplastic yarns by treatment with a stream of fluid stress the importance of treating the yarn with the fluid stream while the yarn tension is substantially zero. See, for instance, U.S. Pat. No. 3,380,242 to Richmond et al.